Diastereoselective Amidoalkylation of (3S,7aR)-6-Benzyl-7-hydroxy-3-phenyltetra- hydro-5H-imidazo[1,5-c][1,3]thiazol-5-one : A Short and Highly Efficient Synthesis of (+)-Biotin

Abstract
A short and highly efficient synthesis of (+)-biotin in 10 steps with 20% overall yield has been achieved from L-cysteine involving amidoalkylation of hydroxy imidazothiazolone 4 via an acyliminium ion intermediate to furnish C-7-substituted imidazothiazolones 5b as the key step.